Manufacture of isopropyl- and homologous esters of aliphatic acids and isopropyl- and homologous alcohols



. as the corresponding alcohols.

Patented Dec. 15,1931

PATENT OFFICE HEBMANN SUIDA, O1 IODLING,

nus'mmnssronon r0 1. e. rmnnmnus'rmn AKTIENGESELLSOEAIET, OF WOBT-ON-THE-m, GERMANY, A. CORPORATION OF GERMANY MANUFACTURE OF ISOPROPYL- AND HOIOLOGOUS ESTEBS OF ALIPEATIG ACIDS AND ISOPBOPYL- No Drawing. Application filed July 1029, Serial R0.

The invention relates to the manufacture of isopropyl-, sec.-butyland homologous esters of aliphatic acidssoluble in water, as well as isopropyl-', sec.-butyland homologous alcohols from dilute ali hatic acids soluble in water and from olefi iies. I have found that by introducing propylene, butylene or homologues thereof or gases containing such olefines into acetic acid of any dilution or another dilute aliphatic acid soluble in water in the presence of small amounts of mineral acids or strong organic acids with or without the addition of metallic salts as catalysts, at temperatures exceeding 100 C. and super-atmospheric pressure, the acetic or other acid esters of isopropyl-, sec.-butyland the homologous alcohols are obtained as well A special method of carrying out the above process consists in-causing dilute acetic acid and olefine gases to react with one another in a continuous process at temperatures exceeding 100 C. in the presence of the auxiliary agents mentioned above atsuch a pressure that the esters and alcohols formed distil continuously into an upright receiver kept under pressure, while the auxiliary agents hereinbefore referred to, in so far as they are not used up in the reaction, remain behind in the reaction vessel.

In accordance w1th the invention acetic acid of any dilution or another dilute aliphatic acid soluble in water reacts readily with olefines with the exception of ethylene at temperatures exceeding 100 C. and-superatmospheric pressure above 10 atmospheres with the simultaneous formation of esters and alcohols, provided that a small amount of strong acid is present as catalyst. Indeed olefines with the exception of ethylene eve? react on dilute acetic acid at elevated temperatures and pressures in the absence of strong acids as catalysts, although a technically satisfactory result is only obtained in.

the presence of strong acids. In order to exclude the known reaction between olefines and strong acids it will be understood that the catalytically acting strong acid is only added in quite small quantities say, 5 per- AND HOIOLOGOUS ALCOEOLS $80,748, and in Austria 'J'uly 21, 1928.

cent or less and is still further diluted by the dilute acid. I

As such catalytically acting strong acids the following are named among others hydrochloric acid, sulphuric acid, hosphoric acid, naphthalene sulphonic acid, benzene sulphonic acid, trichloracetic acid.

he presence of metallic salts exerts under given conditions a favorable influence on the progress of the reaction, in particular silver salts and copper salts react favorably; the influence of these metallic salt catalysts, however, is so small in comparison with the influence of small amounts of strong acid that the pzactical execution of the reaction can only carried out in the presence of a catalytic-ally acting The technical progress and success of this process is based on the fact that dilute waste acetic acid or other aliphatic dilute acid soluble in. water, such as formic or propionic acid, for example, 10%, 15%, 20%, 30% acetic acid, as is obtained as an undesirable and difiicultly utilizable by-product in all kinds of acetylation, can be converted continuously with gases containing olefines in such a way that the acetic acid is transformed amount of the above strong acids.

to readily separable, highly valuable esters reaction mass, is not used up and serves continually for the reaction of fresh quantities of dilute acid with olefines.

The reaction can be carried out in an acid and pressure proof apparatus either intermittently or continuously, the continuous process beingparticularly economical; for example, the process can be carried out by erecting on the reaction vessel a rectifying column, which is likewise maintained under pressure, and'joining thereto a receiver under pressure, the temperature of which is regulated to comply with the requirements. The pressure reaction vessel is charged with dilute acetic acid or other aliphatic acid soluble in water and a small amount of a strong 1 non-volatile acid. A suitable reaction temacetic acid and 5% perature is fixed, the olefine or olefine mixture is forced through the reaction liquid and dilute acetic acid pumped in at the same rate as the ester, alcohol and some water distil off. The ester and alcohol formed as well as some water, which distils with them accumulate in the pressure receiver and excess olefine escapes continuously by a valve in the pressure receiver. The pressure receiver is emptied either continuously or in termittently. The olefine flowing away from the pressure receiver isreabsorbed in the process. The catalytically acting strong acid in the reaction vessel need not be renewed for a long period.

The invention is illustrated by the following examples Example I An acid proof autoclave fitted with a stir.-

-rer is charged with 15% acetic acid, which ester and alcohol. are in the proportion of Ewample- 2 The process is carried out in an analogous manner employin 30% acetic acid. In this case theratio of t e ester to alcohol is 1: 2.5. Instead of a temperature of 150 C. a tem perature lying between'180200 C. can be selected.

EwampZ e 3 A cracking. gas containing considerable quantities of propylene, butylene and homologues is passed through a pressure-tight and acid-resisting cylinder, which contains 10% phosphoric acid at a temperature of 180 C. under a pressure of 50 atmospheres. On the top of the pressure vessel a distillation tube is attached, which is cooled in its lower part and ends in a pressure receiver. The residual gas streams continuously through a throttle valve present in the pressure receiver. The receiver is with advantage maintained at 50 C. In

the receiver a mixture of esters of acetic'acid with alcohols corresponding to the olefines accumulates. The ethylene from the cracking gas takes no part in the reaction but escapes with the residual gas. Instead of phosphoric acid an equivalent quantity of trichloro acetic acid or naphthalene disulphonic acid, benzene sulphonic :1 id or any similar acid can be used.

Example 4 and butylene containing about 60-80% of these olefines) is forced in under a pressure at 20 to 50 atmospheres of 180 C. Simul-' taneous'ly preliminarily heated acetic acid of 20% is pumped in. The mixture of isopropyl and sec.--butyl esters as well as about of isopropyl and sec.-butyl alcohol accumulates in the pressure receiver by a suitable regulation of the reflux condenser, while the residual gas escapes continuously from the pressure receiver through the throttle valve and by washing this gas with water the last' traces of alcohol and ester carried away can be extracted. The method of Working 1s continuous throughout and 20% acetic ac1d is continuously converted into ester and alcohol. The acetic acid is completely utihzed and does not escape with the distillate. Instead of using silver acetate as carrier an equivalent quantity of copper acetate can be used. I

I claim:

1. The process which comprises reacting,

with a higher homologue of ethylene upon a li uid comprising a dilute aliphatic acid solu 1c in water in the presence of no more than 5 per cent of a strong acid, under cond1- tions of elevated temperature above C. and superatmospheric pressure.

2. The process which comprises react ng with a higher homologue of ethylene upon a liquid comprising a dilute al1phat1c ac1d soluble in water in the presence of no more than 5 per cent of a strong inorganic ac1d, under conditions of elevated temperature above 100 C. and pressure above 10 atmospheres.

3. The process which comprises reacting with a higher homologue of ethylene upon a liquid comprising dilute-acetlc ac1d 1n the presence of no more than 5' per cent of a homologue of ethylene upon a liquid dllute 13o aliphatic acid in the presence of no more than per cent of a strong acid and a salt of a heavy metal under conditions of elevated temperature above 100 C. and pressure above atmospheres.

6. The process which comprises reacting with an olefinic gas containing a' higher homologue of ethylene upon liquid dilute acetic acid in the presence of no more than 5 per cent of a strong inorganic acid and a silver salt under conditions of elevated temperature above and pressure above 10 atmospheres.

7. The process which comprises continuously feeding a gas containing a higher homologue of ethylene under conditions of elevated temperature above C. and pressure above 20 atmospheres into a liquid dilute aliphatic acid soluble in water and containing no more than 5 per cent of a strong inorganic acid, the esters and alcohols formed being continuously distilled off under the same pressure and new dilute aliphatic acid being supplied at the rate of the consumption thereof.

8. The process which comprises continuously feeding a gas containing a higher homologue of ethylene under conditions of elevated temperature above 150 C. and pressure above 20 atmospheres into liquid dilute acetic acid containing no more than 5 per cent ofa strong inorganic acid, the esters and alcohols formed being continuously distilled off under the same pressure and new dilute acetic acid being supplied at the rate of the consumption thereof.

9. The rocess which comprises continuously fee 'n a gas containing a higher homologue o ethylene at a temperature of 1 about C. and under a pressure of 20 to 50 atmospheres into dilute acetic acid containing about 20 percent of acetic acid, about 21percent of sulfuric acid and about 1 ercent 0 silver acetate, continuously disti ing oif the acetic acid esters and the non-primary alcohols formed and supplying new dilute acetic acid at the rateof the consumption thereof. 7

In testimony whereof I have hereunto set my hand.

HERMANN SUIDA. 

